In order to transmit payload data in packet-oriented networks, different parameters relating to the transmission are typically negotiated between the communication partners of a payload data link as part of a signaling exchange. Said parameters are referred to below as transmission modes and specify e.g. a codec used for encoding and decoding the payload data.
In this case the transmission modes for the payload data transmission are negotiated such that a communication can take place between the communication partners. For example, mutually compatible codecs or codecs which are supported by both partners are selected by the communication partners. By means of these compatible codecs a payload data link can be set up between the communication partners, while at the same time the choice of codecs used in particular can have an effect on the quality of the payload data transmission and on the bandwidth used for the payload data transmission.
In a packet-oriented network, link sections can make different bandwidth resources available in each case. For example, a packet-oriented voice connection of a teleworker to a terminal device in a LAN (Local Area Network) can be routed via a narrowband telephone line of a public telephone network to a gateway in the LAN and from there forwarded via broadband to the terminal device. In many communication systems it often happens that if a non-compressing codec is selected a connection cannot be set up via the narrowband link section since insufficient bandwidth is available for a payload data link encoded using this codec, whereas if a compressing codec is chosen for the payload data link sufficient bandwidth would still have been available.
Often also, a codec which is highly compressing is chosen for the payload data link and consequently only delivers a reduced payload data quality, even though the network makes a sufficiently high bandwidth available which would have allowed the use of a low-compression codec with better payload data quality.
The selection of the codecs and other transmission modes for a payload data transmission is in this case often made by the endpoints of the connection and is often configured in these. In this case the configuration—e.g. which codecs are used—can be performed on a cross-network or network-area-specific basis.
The U.S. Pat. No. 6,671,367 B1 discloses a method wherein a prioritized list of preferences is transmitted from an originating signaling endpoint to what is termed a Media Gateway Controller, said list being modified by the Media Gateway Controller in such a way that elements which are not supported by an associated Media Gateway are removed and this modified list is transmitted to the Media Gateway.